diff --git a/resources/sshdconfig/src/repeat_keyword.rs b/resources/sshdconfig/src/repeat_keyword.rs
index edf8d4cc5..e27f51c9e 100644
--- a/resources/sshdconfig/src/repeat_keyword.rs
+++ b/resources/sshdconfig/src/repeat_keyword.rs
@@ -78,11 +78,13 @@ pub struct NameValueEntry {
     pub value: Option<String>,
 }
 
+fn default_true() -> bool { true }
+
 /// Input for name-value keyword single-entry operations (e.g., subsystem).
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize, JsonSchema)]
 pub struct RepeatInput {
     /// Whether the entry should exist (true) or be removed (false)
-    #[serde(rename = "_exist", default)]
+    #[serde(rename = "_exist", default = "default_true")]
     pub exist: bool,
     /// Metadata for the operation
     #[serde(rename = "_metadata", skip_serializing_if = "Option::is_none")]
diff --git a/resources/sshdconfig/tests/sshdconfigRepeat.tests.ps1 b/resources/sshdconfig/tests/sshdconfigRepeat.tests.ps1
index ac39caf23..8a2a34d7b 100644
--- a/resources/sshdconfig/tests/sshdconfigRepeat.tests.ps1
+++ b/resources/sshdconfig/tests/sshdconfigRepeat.tests.ps1
@@ -212,5 +212,23 @@ PasswordAuthentication yes
 
             Remove-Item -Path $stderrFile -Force -ErrorAction SilentlyContinue
         }
+
+        It 'Should default to _exist=true when not specified explicitly' {
+            $inputConfig = @{
+                _metadata = @{
+                    filepath = $TestConfigPath
+                }
+                subsystem = @{
+                    name = "testExistDefault"
+                    value = "/path/to/subsystem"
+                }
+            } | ConvertTo-Json
+
+            $output = sshdconfig set --input $inputConfig -s sshd-config-repeat 2>$null
+            $LASTEXITCODE | Should -Be 0
+            # verify subsystem was added (defaulting to _exist=true)
+            $subsystems = Get-Content $TestConfigPath | Where-Object { $_ -match '^\s*subsystem\s+' }
+            $subsystems | Should -Contain "subsystem testExistDefault /path/to/subsystem"
+        }
     }
 }